Apparatus for controlling admission of fuel to a blast furnace



Jan. 18, 1966 F. .KENNEDY 3,229,969

APPARATUS FOR CONTROLLING ADMISSION OF FUEL TO A BLAST FURNACE Original Filed Feb. 14, 1961 2 Sheets-Sheet l his--3 94 I J% l ,1

== 926 sa ae as so lNl/E'A/T'OR FRANK KENNEDY A Iforney 2 Sheets-Sheet 2 F. KENNEDY APPARATUS FOR CONTROLLING ADMISSION OF FUEL TO A BLAST FURNACE Jan. 18, 1966 Original Filed Feb. 14. 1961 United States Patent 3,229,969 APPARATUS FOR CONTROLLING ADMISSION OF FUEL TO A BLAST FURNACE Frank Kennedy, Westmont, Pa., assignor to United States Steel Corporation, a corporation of New Jersey Original application Feb. 14, 1961, Ser. No. 89,166, now Patent No. 3,165,399, dated Jan. 12, 1965. Divided and this application Oct. 3, 1962, Ser. No. 228,147

6 Claims. (Cl. 266-29) This application which relates to apparatus for controlling admission of fuel to a blast furnace is a division of my co-pending application Serial No. 89,166 filed February 14, 1961, now Patent No. 3,165,399. The invention relates more particularly to controlling the admission of fuels such as natural gas, oil, or powdered coal into the tuyeres of the blast furnace. The broad concept of supplying fuel in this manner to replace part of the coke charge is known and the advantages thereof are also known. However, the various methods suggested and used for introducing such fuel have various disadvantages. In general, such controls regulate the flow of gas to the tuyeres based on a percentage of total air flow to all the tuyeres. In blast furnace operation the furnace burden is subject to variations which frequently restrict the flow of air through one or more tuyeres. This reduced flow of air lowers the rate of combustion in the region of the restricted tuyere and may produce a localized cooling. If the flow of natural or coke oven gas or other fuel through the restricted tuyere is not decreased, the rate of cooling at the restricted tuyere is increased so that the troubles at this point are multiplied. Other disadvantages of other methods relate to safety and rapidity of operation.

It is therefore an object of my invention to provide apparatus for introducing air and fuel into the tuyeres of a blast furnace in which a predetermined air-fuel ratio is maintained for both total flow and flow to the individual tuyeres.

Another object is to provide such a control in which the fuel gas to the tuyeres is shut off when the air pressure is higher than the gas pressure.

A further object is to provide such a control in which fuel flow to the individual tuyeres is shut oif when the air flow to that tuyere falls below a predetermined amount.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

FIGURE 1 is a schematic plan view of a blast furnace and the fuel and air supply thereto;

FIGURE 2 is a schematic view of the apparatus of my invention; and

FIGURE 3 is a schematic wiring diagram.

Referring more particularly to the drawings, reference numeral 2 indicates a blast furnace having a plurality of tuyeres 4 arranged around its periphery. Air is supplied to each of the individual tuyeres from a bustle pipe or air manifold 6 through a conduit 8. The air is supplied to the butstle pipe from a stove 10. Cold air is delivered to the stove 10 through a cold blast main 12 having a snort valve 14 associated therewith. The parts so far described are conventional. 'According to 'my invention a fuel gas manifold 16 also surrounds the blast furnace 2 with individual conduits 18 leading from the manifold 16 to each individual tuyere. Assuming that the fuel is gas, it is supplied to the manifold 16 through a gas main 20 having a pressure regulator 22 therein for maintaining the gas pressure constant. An orifice 24 is provided in the cold blast main 12 and a standard flow transmitter 26, such as a Model 1lC25 pneumatic type manufactured by Moore Products Company of Philadelphia, Pennsylvania, is connected to opposite sides of the orifice so as to get an impulse proportional to air flow. A pressure tap 28 is connected to the cold blast main and is connected to a standard pressure transmitter 30, such as a Moore Model 1735 pneumatic type. A thermocouple 32, or other temperature responsive device, is also provided in the gas main 12 and is connected to a standard temperature transmitter 34, such as a Moore Model 33B80. The impulse from transmitter 26 is modified by the impulse from pressure transmitter 30 by means of a standard pressure compensated impulse relay 36, such as a Sorteberg Type SP having square root extraction, so as to compensate for pressure diiferentiations and the impulse from relay 36 is modified by an impulse from transmitter 34 by means of a standard compensated impulse relay 38, such as a Bailey Type AR8062A, in order to compensate for temperature changes of the air blast. The impulse from relay 38 is modified in a standard differential comparison relay 40, such as a Moore Model 68-1, by an impulse from a standard position transmitter 42, such as a Bailey Model 5318487A3, which last named impulse is proportional to the opening of snort valve 14. The impulse from relay 40 is delivered to a standard flow meter and recorder 44, such as 9. Moore Model 5321R, which records the total flow of air to the blast furnace compensated for temperature and pressure. The impulse from relay 40 is also impressed on a standard pneumatic set ratio relay 46, such as a Sorteberg Type R, which in turn is connected to a standard air-gas ratio controller 48, such as a Moore Model M Nullmatic Controller. While the instruments so far described are air operated they may be replaced by other types of standard instruments which may be oil or electrically operated.

An orifice 50 is provided in the gas main 20 and a flow transmitter 52 is connected thereacross. The transmitter 52 may be the same type as transmitter 26 but it is preferred to use a Moore Model ll-C-IOO in place thereof. A pressure transmitter 54, temperature transmitter 56, pressure compensating impulse relay 58 and temperature compensating relay 60 corresponding to devices 30, 34, 36, and 38, respectively, are connected to transmitter 52 in the same manner as devices 30, 34, 36, and 38 are connected to transmitter 26. Temperature compensating relay 60 has its impulse connected to recorder 44 and to air-gas ratio controller 48. The impulse from ratio controller 48 is connected to manual automatic selector 62 which is a standard type such as Moore Model 524-P and then to a standard selector relay 64, such as a Moore Model 58 which is used to modify the signal at low gas flow to prevent total shut-off of the gas. The pneumatic signal from relay 64 is connected to a solenoid operated three-Way valve 66 which may be positioned to pass air 'to the atmosphere or to diaphragm 68D which acts to position gas control valve 68.

Located in each of the conduits 18'leading to the individual tuyeres is an air operated shut-off valve 7 0 and an orifice 72 for measuring gas flow. The position of valve is controlled by a diaphragm 70D. A fluid transmitter 74' of any standard type such as Hagan Model MYP-SIO 335430L(NP) is connected across the orifice 72. The impulse transmitter 74 is connected to pressure switch 76. An air flow transmitter 78, such as a Moore Model 11- C-25, is connected across bustle pipe 6 and conduit 8. The output of impulse transmitter 78 is connected to a standard high-low pressure switch 80 having a dual setting, such as a Barksdale Melatron Model 424E10-L, and also to a standard impulse relay 82, such as a Moore Model 67-25, and then to a solenoid operated three-way valve 84 which either delivers the impulse to diaphragm 7 0D or vents it to atmosphere. It will be understood that each of the tuyeres is provided with this equipment although only one is shown and described.

-tomatically is diverted to the remaining tuyeres.

An air pressure switch 86 is connected to the hot blast main 6 and a gas pressure switch 88 is connected to the gas main 20. The switches 86 and 88 are connected in series with a similar switch 90 connected to the instrument air manifold (not shown) and also in series with a relay coil 92 having normally open contacts 92C and 92C1.1 Contact 92C is connected in parallel with a momentary contact switch 94. A similar push button switch 96 is connected in series with switches 86, 88, and 90. Contact 92C1 is connected in series with solenoid 668 of valve 66. A differential pressure switch 98, which is connected between hot blast manifold 6 and gas main 20, is arranged in series with momentary contact switches 100 and 102 and relay coil 104 having normally open contacts 104C and 104C1. Contact 104C is connected in parallel with switch 100. Contact 104C1 is connected in series with switches 76, 80 and 106 and relay coil 108 having a normally open contact 108C which is connected in series with solenoid 848. At least part of the circuit connected in series with contact 104C1 is repeated for the other tuyeres and additional contacts may be provided for relay 104 to control the circuits if desired or all of the other circuits can be arranged in series with contact 104C1.

In operation, the various instruments are set to suit the desired conditions. The air-gas ratio controller 48 will maintain the desired ratio between air and gas flow by changing the opening and closing of valve 68, compensated signals from air flow transmitter 26 and gas flow transmitter 52 controlling feed-back to ratio controller 48 to insure that the valve '68 is properly positioned. Switches 94 and 96 are closed and if the instrument, air, hot blast air and the fuel gas are at above a pre-set minimum pressure, the switches 86, 88 and 90 will also be closed so that relay coil 92 will be energized. Energization of coil 92 closes contact 920 to lock coil 92 .in when switch 94 is released. Closing of contact 9201 energizes solenoid 66S so as to position, valve 66 to admit the control signal to diaphragm 68D of valve 68. Thus, valve 68 is positioned to maintain the predetermined ratio between air and gas. However, if the pressure of the instrument air, hot blast air or gas falls below the pre-set pressure, the corresponding pressure switch will open to deenergize relay coil 92. This opens contact 92C1 to deenergize solenoid 66S which will position valve 66 to vent the signal from relay 64 to atmosphere. Thus, the control is taken out of operation. Opening of switch 96 will also take the control out of operation.

In controlling the flow of fuel gas to the individual tuyeres, switch 98 is closed as long as the supply gas pressure is higher than the manifold air pressure. To start the control in operation switch 100 is momentarily closed which will energize relay coil 104 since switches 98 and 102 are closed. Energization of coil 104 closes contact 104C to lock it in. Closing of contact 104C1 will energize relay coil 108 if switches 76, 80 and 106 are. closed. If the air flow to the particular tuyere is low due to plugging or other cause, the output signal of its associated transmitter 78 will be of low magnitude and the signal will modulate the valve 70 through relay 82 to a partially closed position. This cut back of gas flow will be proportional to the reduction in air flow until the air flow to the tuyere is reduced to 50 percent of normal. If the signal continues to decrease due to air flow below 50 percent, the valve 70 will close at a more rapid rate. If the air flow continues to decrease, the pressure switch 80 will open if the air flow is reduced to about /3 the normal flow. This will deenergize relay coil 108 and close its contact 108C to deenergize solenoid 84S which will actuate valve 84 to vent the impulse to atmosphere and thus close valve 70 to cut off flow of all gas to the plugged tuyere. The gas flow from plugged tuyeres au- If a tuyere is ruptured the gas flow will increase greatly and the output signal of transmitter 78 will be of such high magnitude that pressure switch 80 will open with the associated valve 70 closing and the gas being diverted to those tuyeres operating normally. If there is a break in the hose connection between orifice 72 and its associated tuyere, the gas flow through orifice 72 will increase, thus opening switch 76 to deenergize relay 108 which deener gizes solenoid 848. This causes valve 84 to vent and shut off valve 70. Manual re-set provided as part of switch 76 prevents automatic re-opening of the valve 70. The switch 106 can be opened if necessary to remove gas from an individual tuyere. Opening of switch 102 takes all the controls of the fuel gas to the individual tuyeres out of operation.

While one embodimentof my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In combination with a blast furnace having a plurality of tuyeres for delivering air to the furnace, an air manifold, and separate branch lines leading from said air manifold to each of said tuyeres, a fuel manifold, separate branch lines leading from said fuel manifold to each of said tuyeres, a valve in each of said fuel branch lines, means for measuring total air flow in said air manifold, means for measuring total fuel flow in said fuel manifold, means operable by signals from said air and fuel flow measuring means to control total gas flow, means for measuring air flow to each individual tuyere, means for measuring fuel flow to each individual tuyere, means operable by signals from said air and fuel flow measuring means of each tuyere to move the fuel valve associated therewith toward closed position as the air flow decreases.

2. In combination with a blast furnace having a plurality of tuyeres for-delivering air to the furnace, an air manifold, and separate branch lines leading from said air manifold to each of said tuyeres, a fuel gas manifold, separate branch lines leading from said gas manifold to .each of said tuyeres, a valve in each of said gas branch lines, means for measuring total air flow in said air manifold, means for measuring total gas flow in said gas manifold, means operable by signals from said air and gas flow measuring means to control total gas flow, means for measuring air flow to each individual tuyere, means for measuring gas flow to each individual tuyere, means operable by signals from said air and gas flow measuring,

means of each tuyere to move the gas valve associated therewith toward closed position as the air flow decreases, and means for closing all of said valves if the air pressure in said air manifold is greater than the gas pressure in said gas manifold.

3. In combination with a blastfurnace having a plurality of tuyeres for delivering air to the furnace, an air manifold, and separate branch lines leading from said air fold, means operable by signals from said air and gas fiow measuring means to control total gas flow, means for measuring air flow to each individual tuyere, means for measuring gas flow to each individual tuyere,.means,operable by signals from said air and gas flow measuring means of each tuyere to move the gas valve associated therewithtoward closed positions as the air flow de-.

creases, means for closing the associated gasvalve when the air flow to said tuyere decreases below a predetermined amount, and means for closing all of said valves if the air pressure in said air manifold is greater than the gas pressure in said gas manifold.

4. In combination with a blast furnace having a plural-.

ity of tuyeres for delivering air to the furnace, an air manifold, and separate branch lines leading from said.

air manifold to each of said tuyeres, a fuel manifold, separate branch lines leading from said fuel manifold to each of said tuyeres, a valve in each of said fuel branch lines, means for measuring total air flow in said air manifold, means for measuring total fuel flow in said fuel manifold, means operable by signals from said air and fuel flow measuring means to control total fuel flow, means controlled by low pressure in one of said air and fuel manifolds to shut oif fuel flow, means for measuring air flow to each individual tuyere, means for measuring fuel flow to each individual tuyere, means operable by signals from said air and fuel flow measuring means of each tuyere to move the fuel valve associated therewith toward closed position as the air flow decreases.

5. In combination with a blast furnace having a plurality of tuyeres for delivering air to the furnace, an air manifold, and separate branch lines leading from said air manifold to each of said tuyeres, a fuel gas manifold, separate branch line-s leading from said gas manifold to each of said tuyeres, a valve in each of said gas branch lines, means for measuring total air flow in said air manifold, means for measuring total gas flow in said gas manifold, means operable by signals from said air and gas flow measuring means to control total gas flow, means controlled by low pressure in one of said air and gas manifolds to shut off gas flow, means for measuring air flow to each individual tuyere, means for measuring gas flow to each individual tuyere, means operable by signals from said air and gas measuring means of each tuyere to move the gas valve associated therewith toward closed position as the air flow decreases, and means for closing all of said valves if the air pressure in said air manifold is greater than the gas pressure in said gas manifold.

6. In combination with a blast furnace having a plurality of tuyeres for delivering air to the furnace, an air manifold, and separate branch lines leading from said air manifold to each of said tuyeres, a fuel gas manifold, separate branch lines leading from said gas manifold to each of said tuyeres, a valve in each of said gas branch lines, means for measuring total air flow in said air manifold, means for measuring total gas flow in said gas manifold, means operable by signals from said air and gas flow measuring means to control total gas flow, means controlled by low pressure in one of said air and gas manifolds to shut off gas flow, means for measuring air flow to each individual tuyere, means for measuring gas flow to each individual tuyere, means operable by signals from said air and gas flow measuring means of each tuyere to move the gas valve associated therewith toward closed position as the air flow decreases, means for closing the associated gas valve when the air flow to said tuyere decreases below a predetermined amount, and means for closing all of said valves if the air pressure in said air manifold is greater than the gas pressure in said gas manifold.

References Cited by the Examiner UNITED STATES PATENTS 1,620,240 3/1927 Smoot 158-119 WHITMORE A. WILTZ, Primary Examiner.

DELBERT E. GANTZ, Examiner. 

1. IN COMBINATION WITH A BLAST FURNACE HAVING A PLURALITY OF TUYERES OF DELIVERING AIR TO THE FURNACE, AN AIR MANIFOLD, AND SEPARATE BRANCH LINES LEADING FROM SAID AIR MANIFOLD TO EACH OF SAID TUYERES, A FUEL MANIFOLD, SEPARATE BRANCH LINES LEADING FROM SAID FUEL MANIFOLD TO EACH OF SAID TUYERES, A VALVE IN EACH OF SAID FUEL BRANCH LINES, MEANS FOR MEASURING TOTAL AIR FLOW IN SAID AIR MANIFOLD, MEANS FOR MEASURING TOTAL FUEL FLOW IN SAID FUEL MANIFOLD, MEANS OPERABLE BY SIGNALS FROM SAID AIR AND FUEL FLOW MEASURING MEANS TO CONTROL TOTAL GAS FLOW, MEANS FOR MEASURING AIR FLOW TO EACH INDIVIDUAL TUYERE, MEANS FOR MEASURING FUEL FLOW TO EACH INDIVIDUAL TUYERE, MEANS OPERABLE BY SIGNALS FROM SAID AIR AND FUEL FLOW MEASURING MEANS OF EACH TUYERE TO MOVE THE FUEL VALVE ASSOCIATED THEREWITH TOWARD CLOSED POSITION AS THE AIR FLOW DECREASES. 